We've got a winner in "Good Will Hunting." The glow goes well beyond a radiant performance by Matt Damon as a misunderstood, rebellious genius. Intimate, heartfelt and wickedly funny, it's a movie whose impact lingers.

"Good Will Hunting," opening today, was written by Damon and co-star Ben Affleck ("Chasing Amy"). A smart cast led by top-billed Robin Williams, along with Minnie Driver and Stellan Skarsgard, keeps it fresh.

The film is a departure for director Gus Van Sant ("My Own Private Idaho") -- this one has warmth as well as edge. That may disappoint hard-core Van Sant fans, but it shows the director applying a sure hand to a more mainstream story without forsaking the offbeat.

Damon plays Will Hunting, a night janitor at the Massachusetts Institute of Technology. He's a tough Boston "Southie" who relishes hanging out with his foul- mouthed Irish-American buddies, a group of aimless rowdies who hit bars and bully guys from other neighborhoods. His best friend, Chuckie, is played with smart-alecky affection by Affleck.

But there's more than swagger and mysterious rage to Will Hunt ing. Behind the tough guy there's a genius. Will can digest encyclopedic knowledge in a sitting -- and he can work out solutions to mathematical problems that frustrate the Nobel laureates at MIT.

His genius is mostly Will's secret. He's as much a victim of it as he is driven by it. A product of working- class values, he never went to college and is stuck in a menial job, his gift undetected by everybody except his Southie pals, for whom the intellectual life promises little reward.

Will's secret, though, is "discovered" by a brilliant professor (Skarsgard, "Breaking the Waves") who takes him under his wing, both fasci nated by and jealous of the kid's abilities. When Will gets arrested for assault and faces prison, the professor turns to a psychologist friend (Williams) to get court-ordered therapy for his violent behavior.

The film, though often riotously funny, is a powerful study of a young man whose tough facade and bullying charm are masks for the monster genius he can't shake. The psychologist, also a genius type, recognizes a soul mate. Confronting each other as equals, they nevertheless both re fuse to budge from their own emotional isolation. "Good Will Hunting" becomes a poignant, embracing drama of hurt, scared humanity learning to reach out.

Damon is sensational. Even in quiet moments, torment seems to roil under his skin. He turns every gesture of defiance and denial into a revelation. His acting is earthy, audacious and intelligent. Williams also turns what might have been a star walk-through into a soulfully rich performance. His character is a kind, wise man, but Williams makes him bristle with feelings that reveal his vulnerability.

Will Hunting's love interest is a British pre-med Harvard student named Skylar (Driver). She is also a bit of a genius, but unlike Will, she's got a handle on the world. Wealthy and bound for Stanford Medical School, she instinctively understands that Will, for all his genius, may always be a man with a hog-tied heart, and she has to move on.

Van Sant's off-center approach helps make an odd collection of characters come alive. The choicest moments are when Will is out with his pals. Here, Van Sant seems most at home.

But his camera is well-tuned to the perhaps more challenging side of the story, when banter takes a back seat to emotional dialogue. The camera seems pleased to linger over the characters' faces as they change, exposing their hearts and touching nerves.